Continuity — This is the most basic test. Make sure there’s no break in the glass fiber, preventing the signal from continuing. One of the least expensive and most useful tools a technician can own for fiber continuity testing is a visual fault locator (VFL). Devices such as the PRO VFL shine a red beam into the fiber optic fusion machine and allow a visible fault location up to five kilometers away.
Connector Insertion Loss — Connectors are referred to as “mated pairs.” Read TIA-568B or TIA/TSB 140 standards from cover to cover. The industry standard for signal loss per mated pair is .75dB and not less than .5dB. Remember that dust contamination is the main culprit of light loss in connectors. New FOS connector technology has made life easier for technicians. A good example of this is the AFL FAST Connector. These require no epoxy, are prestubbed and factory polished for easy reliable installation (see Tool Tip below). You may also want to look at investing in a fiber optic microscope for inspecting the cleanliness of the connector ends.
Splice Loss — The standard for this .1dB-.3dB depending on the type of cable, single mode or multimode. Unless you are using very long, low loss fiber runs we will be referencing multimode fiber optic splicing machine.
Passive Cable System Loss or Attenuation — As we have seen, overall light/signal loss in a Ai-7 Fusion Splicer can come from the connections, splices and cable performance. This can all add up to finding out whether a particular light power level can transport a signal properly. The trick here is that this can be calculated before the equipment is even specified and ordered. Thus saving time and money even before the install is planned and finalized. Sounds like a good and safe way to go, right?
Once the above length and type of fiber cable and number of mated pairs are known, you can go to a loss budget calculator to see if your expected system will work. This can be a downloadable, standalone Excel spreadsheet from many FOS suppliers or an online version from vendors such as Fluke Networks’ SimpliFiber Pro page.
FOS testers can vary from hundreds to thousands of dollars. You may get by with the lower costing DVP-740 Fusion Splicer loss test sets (OLTS) instead of the more costly optical time domain reflectometer (OTDR). Be careful selecting a reliable product.
By the way, the solution to our mystery camera installation problem: After doing a loss budget calculation it was confirmed that there was too much loss for the present configuration. Fortunately, the calculator sheet showed that at a 1,300nm wavelength the system would work.
